﻿namespace 条件判断语句
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入分数 0-100：");
            string input = Console.ReadLine();
            int score = int.Parse(input);
            if(score >= 90)
            {
                Console.WriteLine('A');
            }
            else if(score >= 80 && score <= 89)
            {
                Console.WriteLine('B');
            }
            else if(score >= 60 && score <= 79)
            {
                Console.WriteLine('C');
            }
            else
            {
                Console.WriteLine('D');
            }

            Random random = new Random();
            random.Next(0,5); // 0,1,2,3,4
            int r = random.Next(1,101);
            Console.WriteLine($"r={r}");
        }
    }
}